1. Field
One embodiment of the invention relates to an information processing apparatus such as a personal computer, and a power control method which is applied to the information processing apparatus.
2. Description of the Related Art
In recent years, various types of battery-powerable personal computers, such as notebook type computers or laptop type computers, have been developed. Most of such computers have various power management functions for reducing power consumption amounts. In addition, recently, the technology for reducing the standby power of an AC adapter itself for supplying power to the personal computer has begun to be developed. In the state in which an AC adapter is connected to a commercial power supply, power (standby power) is consumed by the operation of the power supply circuit in the AC adapter even in the case where no power is supplied from the AC adapter to the personal computer.
Jpn. Pat. Appln. KOKAI Publication No. 2008-125270 discloses an electronic apparatus having a function of controlling the operation of a primary-side oscillator included in an AC adapter. In this electronic apparatus, a disable signal is supplied to the AC adapter via a control line which is provided on a power connector of the electronic apparatus, thus being able to stop the operation of the oscillator of the AC adapter.
In the meantime, in offices and factories, many users use personal computers on their desks, with the personal computers being connected to AC adapters. When moving to other places such as a meeting room, the user, in many cases, disconnects the AC adapter from the personal computer and carries the personal computer alone. In such cases, if the AC adapter remains connected to the commercial power supply, useless power (standby power) is consumed by the AC adapter.
In the technique of KOKAI No. 2008-125270, the disable signal is supplied from the electronic apparatus to the AC adapter over the cable. Thus, after the AC adapter is disconnected from the electronic apparatus, the AC adapter can no longer be controlled by the electronic apparatus side. Consequently, if the AC adapter is disconnected from the electronic apparatus while the AC adapter remains connected to the commercial power supply, it is possible that useless power is consumed by the AC adapter.
It is necessary, therefore, to realize a novel function which can reduce useless power that is consumed by an external power supply device such as an AC adapter.